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961.
Bumblebees (Bombus sp.) are eusocial insects with an annual life cycle whose use as pollinator of crops has gained great importance in modern agriculture. Several authors have found that resource use in Bombus species is usually based on the correlation between the proboscis length of the bumblebees and the corolla depth of the flowers. The aim of this study was to determine proboscis length of Bombus atratus and B. bellicosus, two Uruguayan bumblebees, and verify the resource exploitation testing two cultivated species, the red clover and the bird's foot trefoil. Bumblebee foraging activity was recorded in two culture conditions: in a red clover and bird's foot trefoil mixed meadow, and in contiguous plots of these legumes, and the proboscis length of collected foragers was determined. Both species of bumblebees exploited red clover and bird's foot trefoil although they did it in different proportions in all instances tested. The results indicated that the choice of the resources in B. atratus and B. bellicosus was influenced by their proboscis length. Bombus atratus has a longer proboscis and preferably visited red clover, possibly obtaining nectar easier and faster than B. bellicosus, which has a shorter proboscis. Bombus bellicosus used both resources without any clear preference. 相似文献
962.
Cell death has been initially divided into apoptosis, in which the cell plays an active role, and necrosis, which is considered a passive cell death program. Intense research performed in the last decades has concluded that "programmed" cell death (PCD) is a more complex physiological process than initially thought. Indeed, although in most cases the PCD process is achieved via a family of Cys proteases known as caspases, an important number of regulated PCD pathways do not involve this family of proteases. As a consequence, active forms of PCD are initially referred to as caspase-dependent and caspase-independent. More recent data has revealed that there are also active caspase-independent necrotic pathways defined as necroptosis (programmed necrosis). The existence of necroptotic forms of death was corroborated by the discovery of key executioners such as the kinase RIP1 or the mitochondrial protein apoptosis-inducing factor (AIF). AIF is a Janus protein with a redox activity in the mitochondria and a pro-apoptotic function in the nucleus. We have recently described a particular form of AIF-mediated caspase-independent necroptosis that also implicates other molecules such as PARP-1, calpains, Bax, Bcl-2, histone H2AX, and cyclophilin A. From a therapeutic point of view, the unraveling of this new form of PCD poses a question: is it possible to modulate this necroptotic pathway independently of the classical apoptotic paths? Because the answer is yes, a wider understanding of AIF-mediated necroptosis could theoretically pave the way for the development of new drugs that modulate PCD. To this end, we present here an overview of the current knowledge of AIF and AIF-mediated necroptosis. We also summarize the state of the art in some of the most interesting therapeutic strategies that could target AIF or the AIF-mediated necroptotic pathway. 相似文献
963.
964.
965.
de Barros EP Garcia-Pinto AB Machado PY dos Santos Pereira MJ de Carvalho JJ 《Journal of molecular histology》2011,42(4):323-331
The incidence of chronic renal diseases is increasing worldwide, and there is a great need to identify therapies capable of
arresting or reducing disease progression. The current treatment of chronic nephropathies is limited to angiotensin-converting
enzyme inhibitors and angiotensin receptor blockers, but increasing clinical and experimental evidence suggests that statins
could play a therapeutic role. Ultrastructural studies have shown the presence of gap junctions within all the cells of the
glomerulus and podocytes have been found to contain primarily connexin-43. The present study aims to observe the beneficial
effects of rosuvastatin on structural and ultrastructural renal morphology and on glomerular connexin-43 expression in normotensive
rats and spontaneously hypertensive rats (SHR). Rats were randomly allocated into four groups: WKY-C: normotensive animals
no receiving rosuvastatin; WKY-ROS: normotensive animals receiving rosuvastatin; SHR-C: hypertensive animals no receiving
rosuvastatin; SHR-ROS: hypertensive animals receiving rosuvastatin. Our results show no differences in blood urea, creatinine,
uric acid and creatine phosphokinase levels between the groups, however, there was an decreasing of 24-h protein excretion
in SHR-ROS. Capsular area in SHR-ROS was decreased, however, there was no alteration in urinary space. By transmission electron
microscopy the slit diaphragm and podocyte foot processes were more preserved in SHR-ROS. By scanning electron microscopy
the podocyte foot processes were more preserved in SHR-ROS. Increased connexin-43 immunofluorescence was observed in glomeruli
of WKY-ROS and SHR-ROS. In conclusion, we hypothesize that renal pleiotropic effect of rosuvastatin can be a therapeutic tool
for improving kidney ultrastructure and, consequently, renal function in hypertensive individuals. 相似文献
966.
Karina Vanessa Hmeljevski Ademir Reis Tiago Montagna Maurício Sedrez dos Reis 《Conservation Genetics》2011,12(3):761-769
Dyckia ibiramensis is a naturally rare, endemic and threatened bromeliad which occurs naturally on 4 km of rocky river outcroppings in Southern
Brazil. For this study, subpopulations of the species were characterized based on size and genetics, to compile information
for in situ and ex situ conservation strategies. A census of the rosettes was undertaken for each subpopulation and seven allozyme polymorphic loci
were used to estimate genetic diversity and structure of adults and offspring and assess the mating system. In general, the
subpopulations were small and most of the rosettes were aggregated into clumps. The species showed a high genetic diversity
([^(H)]e = 0.219 \hat{H}_{e} = 0.219 ) and significant fixation index ([^(f)] = 0.642, \hat{f} = 0.642,
P ≤ 0.05). The estimate of differentiation among all adult subpopulations indicate pronounced genetic structure ([^(G)]¢ST = 0.674 \hat{G}^{\prime}_{ST} = 0.674 ). D. ibiramensis has a mixed mating system and multilocus outcrossing rates [^(t)]m \hat{t}_{m} were variable between subpopulations. This study demonstrates the importance of in situ preservation of all subpopulations
for the maintenance of species diversity. For effective ex situ conservation, it would be necessary to collect seeds from 52 to 99 seed-rosettes, depending on the target population. 相似文献
967.
Several Gram-negative bacterial pathogens have developed type III secretion systems (T3SSs) to deliver virulence proteins
directly into eukaryotic cells in a process essential for many diseases. The type III secretion processes require customized
chaperones with high specificity for binding partners, thus providing the secretion to occur. Due to the very low sequence
similarities among secretion chaperones, annotation and discrimination of a great majority of them is extremely difficult
and a task with low scores even if genes are encountered that codify for small (<20 kDa) proteins with low pI and a tendency
to dimerise. Concerning about this, herein, we present structural features on two hypothetical T3SSs chaperones belonging
to plant pathogen Xanthomonas axonopodis pv. citri and suggest how low resolution models based on Small Angle X-ray Scattering patterns can provide new structural insights
that could be very helpful in their analysis and posterior classification. 相似文献
968.
Moreira JS Almeida RG Tavares LS Santos MO Viccini LF Vasconcelos IM Oliveira JT Raposo NR Dias SC Franco OL 《The protein journal》2011,30(1):32-38
Heavy agricultural losses are closely related to attacks by insect-pests and phytopathogens such as bacteria and fungi. Among
them, the fungus Botrytis cinerea can cause gray mold in more than 200 different species of plants, and is considered a challenging problem for agribusiness.
Fungicides are commonly used to control this pathogen because they are fast-working and easy to apply. However, the continuous
use of fungicides may promote the selection of resistant fungi and can also cause profound contamination in ecosystems. Aiming
to find alternative strategies to solve these problems, several studies have focused on searching for plant proteins and peptides
with antifungal activities (AFPs). With this in mind, this report shows the isolation and characterization of two novels antifungal
proteins from flowers of rosemary pepper (Lippia sidoides Cham.) with 10 and 15 kDa. Isolation was performed by using an Octyl-Sepharose hydrophobic column. In vitro bioassays indicated
that isolated proteins were able to inhibit B. cinerea development, but were not effective against all bacteria tested. Moreover, N-termini sequences indicate that both proteins
showed sequence homology with NBS–LRR R proteins with a lower molecular mass, suggesting possible protein fragmentation. Data
reported here could help in the development of biotechnological products for crop protection against phytopathogenic fungi
in the near future. 相似文献
969.
de Lira FA Farias Mde S de Figueiredo AF Gil Fdos S dos Santos MA Malheiros BV Ferreira JE Pinheiro JC Treu-Filho O Kondo RT 《Journal of molecular modeling》2011,17(7):1621-1624
In a previous article, we used Hartree-Fock (HF) theory to study the piezoelectricity in BaTiO3. In this paper, we applied the Douglas-Kroll-Hess second order scalar relativistic method to investigate the possible piezoelectric
properties in the perovskite YFeO3 structure, which has not yet been studied experimentally. The 30s20p13d and 31s21p17d Gaussian basis sets for the Fe (5D) and Y (2D) atoms, respectively, were built with the Generator Coordinate HF method. After contraction to [13s7p5d] and [13s8p7d],
in combination with the 20s14p/6s4p basis set for the O (3P) atom from literature, they had their quality evaluated using calculations of the total and the orbital energies for the
2FeO+1 and 1YO+1 fragments. The dipole moment, the total energy, and the total atomic charges in YFeO3 in Cs space group were calculated. The results and the analysis lead us to believe that the perovskite YFeO3 does not present piezoelectric properties. 相似文献
970.
Andrade RF Rocha-Neto IC Santos LB de Santana CN Diniz MV Lobão TP Goés-Neto A Pinho ST El-Hani CN 《PLoS computational biology》2011,7(5):e1001131
This paper proposes a new method to identify communities in generally weighted complex networks and apply it to phylogenetic analysis. In this case, weights correspond to the similarity indexes among protein sequences, which can be used for network construction so that the network structure can be analyzed to recover phylogenetically useful information from its properties. The analyses discussed here are mainly based on the modular character of protein similarity networks, explored through the Newman-Girvan algorithm, with the help of the neighborhood matrix . The most relevant networks are found when the network topology changes abruptly revealing distinct modules related to the sets of organisms to which the proteins belong. Sound biological information can be retrieved by the computational routines used in the network approach, without using biological assumptions other than those incorporated by BLAST. Usually, all the main bacterial phyla and, in some cases, also some bacterial classes corresponded totally (100%) or to a great extent (>70%) to the modules. We checked for internal consistency in the obtained results, and we scored close to 84% of matches for community pertinence when comparisons between the results were performed. To illustrate how to use the network-based method, we employed data for enzymes involved in the chitin metabolic pathway that are present in more than 100 organisms from an original data set containing 1,695 organisms, downloaded from GenBank on May 19, 2007. A preliminary comparison between the outcomes of the network-based method and the results of methods based on Bayesian, distance, likelihood, and parsimony criteria suggests that the former is as reliable as these commonly used methods. We conclude that the network-based method can be used as a powerful tool for retrieving modularity information from weighted networks, which is useful for phylogenetic analysis. 相似文献